Field of the Invention
The invention relates to a method for transmitting data packets according to a packet data service in a cellular mobile radio network provided for voice and data transmission.
International application WO 95/16330 discloses a plurality of devices and a mobile station for transmitting data packets, which devices permit optimized transmission of the data packets by setting up logic packet data channels. The data packet-specific devices are implemented entirely or partially in the components of a GSM mobile radio system. The data packets are transmitted from and to the mobile station on the packet data channels by using specific packet data protocols.
European patent EP 0 642 283 discloses a mobile radio system in which, in order to reduce the costs for the subscriber with respect to the transmission of data packets in the mobile radio system, a virtual channel is set up by exchanging and storing parameters in a mobile station and a fixed station, which channel permits a rapid setup of a real data communication channel and is maintained during the transmission pauses of the data packets in order to speed up the restoration of the real data communication channel.
In cellular mobile radio networks, such as the GSM mobile radio network (Global System for Mobile Communication), for example, for voice and data transmission, an excessively high signalling load occurs in the case of brief data transmissions. As a rule, a signalling protocol, which ensures there is an exchange of subscriber-specific and network-related information, is initially set up for the transmission of data. A dedicated channel is made available for the transmission of signalling information. After the signalling protocol, a data protocol for the transmission of useful data is set up, in which case a database inquiry can also be intermediately connected in advance while the channel is seized.